Bioconversion refers to converting organic materials (generally wastes) into useful byproducts by processes, such as fermentation, involving living organisms. Bioconversion is also generically known as anaerobic digestion (AD), which is a process commonly used for pollution control in municipal sewage treatment and livestock waste handling. Bioconversion technology can also be applied to other organic “waste” streams, which might not otherwise be “treated” or “treatable”. Some examples of these types of waste are: pre- and post-consumer food waste, “green” waste (cut grass, shrub and tree trimmings, etc.), waste paper (magazines and junk mail, mixed residential, etc.), FOG wastes (fats, oils, and grease), and “high-strength” wastewaters. The organic waste can also come from industrial processes such as food processing (plant or animal), plant materials following industrial processing i.e. residues after extraction of oil.
Anaerobic digestion requires heat input in order to maximize the rate of conversion. However, known digesters do not have a ready source of heat input. Further, a typical digester is used to produce a digester gas, largely methane and carbon dioxide, which can be burned to produce electricity. In the absence of tax or other government incentives, electricity is a relatively low-value product.
It would be advantageous to provide anaerobic digesters and systems including such anaerobic digesters that can provide more valuable products than electricity, and which have a source of heat to accelerate the rate at which biomass is converted.
The present invention provides such an anaerobic digester system and overall bioconversion process.